Determining the correct valve opening and closing points

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digger
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Re: Determining the correct valve opening and closing points

Post by digger » Mon Apr 15, 2019 10:53 pm

GARY C wrote:
Mon Apr 15, 2019 9:51 pm
digger wrote:
Mon Apr 15, 2019 9:47 pm
GARY C wrote:
Mon Apr 15, 2019 9:37 pm

I will take you serious on that when you say the same to Jon and others that post little to nothing in this context.
do you have an example where they have done the same ?
1D... read the thread!

EDIT>>> Page 5 would be a good start. On the flip side do you have evidence of him ever giving any useful info to this subject?
Jon posted a cam program with a guide how to use it

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Re: Determining the correct valve opening and closing points

Post by GARY C » Tue Apr 16, 2019 1:27 am

digger wrote:
Mon Apr 15, 2019 10:53 pm
GARY C wrote:
Mon Apr 15, 2019 9:51 pm
digger wrote:
Mon Apr 15, 2019 9:47 pm


do you have an example where they have done the same ?
1D... read the thread!

EDIT>>> Page 5 would be a good start. On the flip side do you have evidence of him ever giving any useful info to this subject?
Jon posted a cam program with a guide how to use it
I have seen his program for comparing lobes, it looks useful but not sure how you would use it to determine a cam for an engine.
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THE ABOVE POST IN NO WAY REFLECTS THE VIEWS OF SPEED TALK OR IT'S MEMBER AND SHOULD BE VIEWED AS ENTERTAINMENT ONLY...Thanks, The Management!

digger
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Re: Determining the correct valve opening and closing points

Post by digger » Tue Apr 16, 2019 1:37 am

GARY C wrote:
Tue Apr 16, 2019 1:27 am
digger wrote:
Mon Apr 15, 2019 10:53 pm
GARY C wrote:
Mon Apr 15, 2019 9:51 pm


1D... read the thread!

EDIT>>> Page 5 would be a good start. On the flip side do you have evidence of him ever giving any useful info to this subject?
Jon posted a cam program with a guide how to use it
I have seen his program for comparing lobes, it looks useful but not sure how you would use it to determine a cam for an engine.
From memory take a good known similar engine and match the numbers

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Re: Determining the correct valve opening and closing points

Post by GARY C » Tue Apr 16, 2019 2:01 am

digger wrote:
Tue Apr 16, 2019 1:37 am
GARY C wrote:
Tue Apr 16, 2019 1:27 am
digger wrote:
Mon Apr 15, 2019 10:53 pm


Jon posted a cam program with a guide how to use it
I have seen his program for comparing lobes, it looks useful but not sure how you would use it to determine a cam for an engine.
From memory take a good known similar engine and match the numbers
I guess that would work if you knew someone with the exact same engine that was willing to give you all the data but then why not just run the same cam that they are?
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THE ABOVE POST IN NO WAY REFLECTS THE VIEWS OF SPEED TALK OR IT'S MEMBER AND SHOULD BE VIEWED AS ENTERTAINMENT ONLY...Thanks, The Management!

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Re: Determining the correct valve opening and closing points

Post by novadude » Tue Apr 16, 2019 2:18 am

digger wrote:
Mon Apr 15, 2019 9:20 pm
RevTheory wrote:
Mon Apr 15, 2019 9:02 pm
Even DV's overlap charts, that I agree could probably use some better clarification, will get you well within the "squabbling over a couple of degrees" range of person opinion.

At least 128 gets you an LSA that would take dyno testing to improve upon, assuming it's used where it's supposed to be used. In a normal world, something like that would be welcomed.
Drip feeding info does not help.
Normally one post everything in the one spot so the equation and the assumptions or limitations with its use are known. Some of the early stuff presented made it sound like it could be used for anything and everything but now the horse has bolted.....
I will agree with the “drip feeding” comment. I’ve seen 131, 132, 133.5 all posted as the BBC constant to use. Does the .91 correction factor apply? I have no idea. The actual overlap chart posted in DV’s BBC book is way out to lunch, unless it has been corrected in subsequent printings.

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Re: Determining the correct valve opening and closing points

Post by GARY C » Tue Apr 16, 2019 2:27 am

novadude wrote:
Tue Apr 16, 2019 2:18 am
digger wrote:
Mon Apr 15, 2019 9:20 pm
RevTheory wrote:
Mon Apr 15, 2019 9:02 pm
Even DV's overlap charts, that I agree could probably use some better clarification, will get you well within the "squabbling over a couple of degrees" range of person opinion.

At least 128 gets you an LSA that would take dyno testing to improve upon, assuming it's used where it's supposed to be used. In a normal world, something like that would be welcomed.
Drip feeding info does not help.
Normally one post everything in the one spot so the equation and the assumptions or limitations with its use are known. Some of the early stuff presented made it sound like it could be used for anything and everything but now the horse has bolted.....
I will agree with the “drip feeding” comment. I’ve seen 131, 132, 133.5 all posted as the BBC constant to use. Does the .91 correction factor apply? I have no idea. The actual overlap chart posted in DV’s BBC book is way out to lunch, unless it has been corrected in subsequent printings.
I have only seen 132, the .91 is used on all 3 engine family's so I think that would make it the constant in the equation not a correction factor.
I have not done enough Big Block stuff to know what they are I would want for overlap.
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THE ABOVE POST IN NO WAY REFLECTS THE VIEWS OF SPEED TALK OR IT'S MEMBER AND SHOULD BE VIEWED AS ENTERTAINMENT ONLY...Thanks, The Management!

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Re: Determining the correct valve opening and closing points

Post by digger » Tue Apr 16, 2019 4:25 am

GARY C wrote:
Tue Apr 16, 2019 2:01 am
digger wrote:
Tue Apr 16, 2019 1:37 am
GARY C wrote:
Tue Apr 16, 2019 1:27 am

I have seen his program for comparing lobes, it looks useful but not sure how you would use it to determine a cam for an engine.
From memory take a good known similar engine and match the numbers
I guess that would work if you knew someone with the exact same engine that was willing to give you all the data but then why not just run the same cam that they are?
i think it was setup to be dimensionless for lack of a better word so that you didnt need to be doing the same engine to get the same "characteristics" im sure he will explain it if he sees these posts .

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Re: Determining the correct valve opening and closing points

Post by RevTheory » Tue Apr 16, 2019 8:19 am

digger wrote:
Mon Apr 15, 2019 9:20 pm
RevTheory wrote:
Mon Apr 15, 2019 9:02 pm
Even DV's overlap charts, that I agree could probably use some better clarification, will get you well within the "squabbling over a couple of degrees" range of person opinion.

At least 128 gets you an LSA that would take dyno testing to improve upon, assuming it's used where it's supposed to be used. In a normal world, something like that would be welcomed.
Drip feeding info does not help.
Normally one post everything in the one spot so the equation and the assumptions or limitations with its use are known. Some of the early stuff presented made it sound like it could be used for anything and everything but now the horse has bolted.....
Do you guys pitch an absolute shit-fit when you get an updated version of your 1D program, Pipemax, Controlled Induction (programs that can cost hundreds) that had more inputs or revised outputs or is your outrage reserved for David who gave you something for free?

There never seems to be a shortage of people sitting on the edge of their seats eager to complain about something.

Edit: That wasn't a dig at anyone personally, well, maybe a few but not "digger." This junk makes its rounds once a year or so and I'm always baffled by people's eagerness to attack. It takes far less time to see where how to use it than they spend arguing on the internet about where and how to use it.

I'm sure if David's crystal ball was working, he'd have made sure to specify its use with 45* seats or given a way to work around different angles.

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Re: Determining the correct valve opening and closing points

Post by Stan Weiss » Tue Apr 16, 2019 11:01 am

There is only so much one can do with a simple one line formula and while charts give you more to work with it still lets somethings up to interruption. At minimum you would need a full page of computer code for the basics. You could then match up that output to catalog cams for best fit and have something like this.

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Re: Determining the correct valve opening and closing points

Post by RevTheory » Tue Apr 16, 2019 11:42 am

Everyone would argue about the code :D

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Re: Determining the correct valve opening and closing points

Post by mekilljoydammit » Tue Apr 16, 2019 11:47 am

Everyone's going to argue about something or other anyway.

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Re: Determining the correct valve opening and closing points

Post by ClassAct » Tue Apr 16, 2019 12:19 pm

I'm asking a question because I truly don't knew the answer. Wasn't Pipe Max developed from empiracle data? Seems I read an article or maybe watched a video and that's what I remember.

Pipe Max has been proven many times over. Just asking for clarification.

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Re: Determining the correct valve opening and closing points

Post by GARY C » Tue Apr 16, 2019 12:25 pm

The problem is all this cross camming going on now days, when I was a kid cams knew what they were and they were proud, you didn't have dirt cams pretending to be street cams and drag cams, they were good ole hard working dirt cam and they were proud of what they did, lap after lap!

I blame it on those autocrossers... everyone knows a parking lot is for parking, not for racing.

Now you got cams posting pictures of them selves online at each and every event they attend, where will it end?
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Re: Determining the correct valve opening and closing points

Post by SchmidtMotorWorks » Tue Apr 16, 2019 12:35 pm

CAM Flow RPM does not require identical engines.
The point of it is that if you have an engine and like the characteristics of it, you can make a similar engine have similar characteristics.
You can also try combinations to see how they compare.

It takes hundreds of carefully crafted code to do just that. It is vastly more comprehensive than any single line formula.
And it allows you to duplicate characteristics. In my experience getting the desired characteristics is the most important goal to satisfaction with you combination.
http://www.schmidtmotorworks.com Aerospace Machine Work: Prototypes, Tooling, Molds.

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Re: Determining the correct valve opening and closing points

Post by F-BIRD'88 » Tue Apr 16, 2019 1:38 pm

The big trouble with DV's overlap pie chart is that what cam lobe check height is not stated. Is it @ " advertized duration" , or @ running real Lash point duration. Or @ .015" or @.020" (solids) or @ .004" or @ .006" (hyds) ?? Or.....?

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